Color television



Jan. 19, 1954 M. v. KALFAIAN COLOR TELEVISION 8 Sheets-Sheet 2 FiledDec. 8, 1951 INVENTOR. 4Zf

Jan. 19, 1954 M. v. KALFAIAN 6, 6

I COLOR TELEVISION Filed Dec. 8, 1951 8 Sheets-Sheet 4 5 GATE GATE SAW

.BLQ AHPL/T PHASE VIDEO 3 LIN/76R INVERTER 5/6 NALS GATE PUZSES AMSAHPLER WAVE SHAPER POWER AMPLIFIER WAVE fn/ IXER 8c ANTENNA WAVE AMSHAPER l6 SAMPLER AM GATE PI/ NODUIA PULSES GATE ERT R 13 mm: 1 9LIM/TER GATE IN V EN TOR.

HALF-WAVE RECTIFIER TURAT- VIDEO-TRANSMIT rgn 5- 4 fill-WAVE RECTIFIERJan. 19, 1954 M. v. KALFAlAN COLOR TELEVISION 8 Sheets-Sheet 6 FiledDec. 8, 1951 I I I m m Jan. 19, 1954 M. v. KALFAIAN 2,666,806

COLOR TELEVISION Filed Dec. 8, 1951 s Sheets-Sheet VERT. & HORIZ. P1 P64 (ODD-LINE) X i HORIZONTAL X" i I L L Pq SYNCHRON/ZING -PUL5E5 ROM W050 Z9 3 GATE 2 GATE 33 180 GATE GATE I800 GATE 1 1 32 PULSE-GENERATORINVENTOR.

PHASE MODULATOR 0F SYNC-PULSES ,4.

1954 i M. v. KALFAIAN 6,

COLOR TELEVISION Filed Dec. 8, 1951 a Sheets-Sheet a I 11m I l i L rfm+f fz PULSES Z VIDEO 7 RECEIVER PULSE y IRANSM/TTER [ca GENERATOROSCILLATOR AM AF GATE DE 7E6 TOR AMPLIFIER INTERFERENCE METER cUT-QFFFig.1!)

IOKC BAND-PASS SPEAKER AM-AUDlO-DETE TOR I AMPLIFIER RED-VIDEO AMPLIFIER7 W050 PH-DEIECTOR gg m-vmzo L AMPLIFIER IOKC-W/DE REJEUIOIV- I VIDEOBLUE- vmzo FILTER AM-DETECTOR AMPLIFIER RECEIVER Fig.1]

AM'PLITUDE Y 35' LIMITER V RF & If 5g RED 3: AMPLIFIER ro IOKC- PH.-

IBII III M ..I [gnaw/DE AMPLIFIER Manna/v- F/LTER TRI-COLOR I IIMAGE-TUBE I l VIDEO AM-DET. u Salim/#623016. 3 l v k I u PIA-INVERTER kSUB-DIVIDER 1.5m" 5, DET. GREEN F AMPLIFIER MODIFIED ARRANGEMENTINVENTOR.

OF RECEIVER Patented Jan. 19, 1954 UNITED stares PATENT O-FFIE comeTELEViSIODt- Meguerv. Kemaian, usages; caiir: Application-December s,1951; serial No; 2605821 12 Claims, (01. 178-52.)-

1' r This invention relates to color televis on, and more particularly.to provide improved methodsndmen r. th a s fine ar iionof colortelevision signals. Qne object of the inv en'- tion is to transmit videosignals representing three primar colors over simultaneous amplitude andphase modulation f theoarrier wavelwhereby first, to provi .e accuratecolor selection" at thereceiving end without the necessity OfCOIOY-SYD-chronizing waves,.. and second to provide h gh fidelity conveyance oftfie' video signals by utilizirig doL lble-sidbahdi transmission of thecarrier wave. Another objct of the invention is to provid methods and.means; of seanning colorg'pic tures', which according to the physilogical behavior of the human" eye it is capable ofiuterpretifigrepetitious pfo tion of colored pictures, protiu'es fiec'tively thesame'amount of chromatic information on tfi'viewirig screen as it wouldordinarily for mention n p ctures-by the same amount of'video cmoonentsithatare avail-' able in given chanhelband. Still another objectof the invention isto' provide metho'dsj and means for conveying pi turesyfrrchronizing signails over phase modulation of the carrier wave,wheijeby to provide greater Ccuifla yf ifi" p'ifc'ture synchronizationthan is possible by; the conventional serratecl' waye' om A furtherobject of the invention is to as the sound wave oyer an amplitudeodulatejd arri'er waye having the samerunuame a1 frequency as of thevideo= carrying" wave ithout encountering cros's-inten Terence, A stillfufther' object ofthe' invention is to provide methods and meansadapted'to receive the particular type of transmission; whereby toprovide a omplete ystem of color television. Although the present inventorfisnovel in its rofnh, various distinct 'ih'yefitibfie are disclosediii in order to r nter completecolor tele v system, the ves cles-tea resof which may be; 'lj frr d to by my relfitdj if. S. Patent N6: 2558,4891granted June and copending affiiliations; the serial is of which are: 75601 Juries, W semester" 23; T952, 7 3;I4 5, fiecember 22-, 1947, noPatent 'NQ. 2}587,-734; March 1 952; 3 ,318, Jamar-2y 20'; 1 948,ssesses its-25159361 Otto-- bi 28, I952 II, I95I-, the CHIS A 13y iil-"ald' baii't 6f the ond this amount of image elements? will producevisually acceptable monochrome pictures; But; in color televisions eachimage. elementz must-be reproduced in three primary-color components.which reduces the total. number of image 6187*- mentstoabout 2,? millionper; second. While this reduction of image elements willapparentlyimpair the image-resolution of monochrome pic tures it isassumed (accordingto-= actual tests) that'the presence of colors willsomewhat cox-n pensate for the loss oi image details. Physiologica-l:aspects of. the. human eye have I beenv consid-y ered, and accordinglyvarious method'sof con. structing. color pictures on the viewing; screenhave been proposed, in order to effect maximum: pictorial:detailutilizing. whatever amount oi image or color is ayailabl ein thestandard-6 megacyclechannel band of. these methods, themes 'entlystandardizedv fieldesequentia-L system 911611 the generally know-ndot'sequential mixed: highs system are; of;. current. issues. Each: of}these systems has a diffierent advantage over. the other. Forv example,the former is theoretically capable of producingtrue-color pictures withre,

duced; image detail,v whilev the latter is capable. of; renderingfineimage detail but with. reduced color details Thelat'ter system is basedupon the: assumption that the eye. cannot distinguish be tweenmonochrome. and' chromatic images inth fine detail, under usual viewingconditions, Suchv an assumption however may apply only to mov-.- ingobjects, as the eye is definitely capable of seeing fine color-detail instationary objects; and

under usual conditions most of the. viewing screen.

comprises stationary objects. v

To: briefly differentiate varous conditions in which the eye is capableof seeing colored pic.- tures; assume that a moving colored objl'ect isproduced on the. viewing screen in. its first primary=co1or at the firstmoving position; in its second primary-color at the secondmoving-positi'on; and in its third primary-color at the thirdmoving-position. In the case that the object. covers a large viewingarea with few highelights, the eye can easily distinguish the object inall threeposi-tions in three separate colors; with. some rendition ofthe three-color hue. This may be preven by the fact that, in thefield-sequential extreme rapid" rateof' 144 fields per second. How

ever, when the object has intricate coloi" detail, the eye cannotinterpret the differences of color in elementally adjacent areas, andwill average out into a new color. On the other hand, if the object hasno movement of its own and moves steadily against a stationarybackground scene, the eye can follow its movement very easily, andtherefore, the eye can see all the color-detail as if it were stationaryon the screen. For example, the pictorial details of the body of arunning horse can be easily seen, but the legs will appear as a blurr.It follows therefore, that the eye can definitely see fine-detail instationary objects, whether it be in color or black and white; and candefinitely see separate primary-colors of massive objects in movingpositions; but cannot detect fine-detail in moving objects. Under theseviewing conditions, it is obvious therefore that, in field-sequentialsystem the color-sequence cannot possibly be reduced below the presentlyprac ticed frequency rate of 144 fields per second. Similar inefficiencywill be had if all the image elements were scanned and conveyedinsimultaneous primary-colors, or in a sequence of three primary-colors,the system of the latter of which may be termed as, dot-sequential-colorsystem. The reason for this inefficiency is that, constructing eachimage element in three primary-colors in such short elemental time is awaste, because the eye cannot respond to elemental changes in color orimage, at a slow frequency rate of about 10 per second; in contrast tothe 144 massive color-fields per second. Thus by taking advantage ofsuch behavior of the human eye, we may reverse the dot-sequentialcolorsystem into dot-sequential-image system, to retain all the availableimage-detail, and still produce all the imageelements in full threeprimary colors; in contrast to the very little color that is availablein the mixed-highs system.

Various methods of scanning may be employed for the presently proposeddot-sequential-image system. In one mode, all the. image elements in apicture-frame are scanned in one of their pri mary colors, but soarranged that, the adjacent image elements will have different primarycolors, so as to render mutual aid in visually effecting three-colorhues. Then on the succeeding second and third frame periods each imageelement is further resolved into the final three-color hue. Adhering tothe standard 30 frames per second, each image element is constructed inits final color inone tenth of a second. But this rate is not visuallyslow, because the whole picture is still constructed in & second, andeach pictureframe will in most part appear in full-color by way of theelementally-different adjacent colors, since as stated above, the eyeresolves elemental colors into massive colors while the object is inmotion; even in the slow frequency rate of 1 6 second, without flickeror twinkle of image or color. Accordingly, the, object of the presentinvention is to provide methods and means of scanning color pictures, inwhich successive image elements are scanned in one of their primarycolor components, in a mode, as adjacent image elements to consistsubstantially of different primary color components, so as to visuallyeffect three color hues in each picture-frame; and change the sequenceof elemental color components of adjacent image elements duringsuccessive frame periods, whereby to further resolve said elementalimages individually into their three color hues, and thus utilizeeffectively all the image elements in a monochrome system inconstructing the picture, plus; visually effecting three-color hueswithout sacrifice in color detail.

' ial-sideband transmission system.

Various dimculties had previously been experienced in color television,in which accurate colorsynchronization and high fidelity signaltransmission had been shown to be of primary importance for thesuccessful operation of the colorsystem. With regard to previousproposals, precise color-synchronizing method or system appears to benon-existent at this time. For example, referring to the newly revisedform of mixed-highs system (known as NTSC oscillating color system),there is employed a local oscillator at the receiving end, whichoscillates at the subcarrier frequency. To ensure synchronization, thereis transmitted a burst of sine wave after each sync pulse, whereby thissine waveadjusts the phase angle of the local oscillation. After suchphase adjustment, the local oscillator continues oscillating at itsnatural frequency, for color distribution, up to the end of the line.But if at the end of the line this oscillation had shifted of a cycle,there will occur 100% color overlap, with gradual color cross-talkbetween the two edges of the picture.

With regard to highfidelity signal transmis-- sion of video signals, ithad been shown by pre-' vious tests that, reproduction of pictures innatural color is dependent upon superposition of differentprimary-colors having definite brightness levels. Such high fidelityreproduction is not possible Withthe presently standardized vestig- Inthis type of modulation, the high frequency amplitude variations mustfirst be pre-distorted at the transmitting end in comparison with astandard set, so that the reproduced picture at the receiving end may beintelligible. Even with such monotoring, the ideal amplitude correctioncannot be realized; although it may be satisfactory for monochrometelevision.

Accordingly in the preferred embodiment of this invention, there isprovided a novel method of simultaneous amplitude and phase modulationof the carrier wave, whereby first, to provide accurate color selectionat the receiving end without the necessity of color-synchronizing waves,

" and second, to provide high fidelity conveyance it may be assumed thatin all color television sysmultaneously, then the time allotted toconvey of the video signals-by utilizing double-sideband transmission ofthe modulated carrier wave.

In another embodiment of the invention there is provided'acolor-sequence reversing switch, so that the sequence of phasemodulation may be reversed at elemental scansion intervals, in order toconvey the signal of whichever primary color- (second or third) ispresent at an elemental time. To describe the purpose of this operation,

tems each image element will contain a maximum of three primary-colorcomponents. If it were the case that every one of the image elements hadcontained all the primary colors sithese components in any color-systemwould be utilized at the maximum efficiency. However, such is not thecase in colored-pictures, and in v the major part of one picture-framethe majority of elemental images will contain only one or two primarycolors simultaneously. Hence, the time allotted for conveying themissing primary colors will be completely wasted, and result in poorimage detail. In order to utilize most of the time allotted forconveying V the three primary-color modulation to convey videocomponents the GREEN color; assigning phase modulation mirth-e carrierwave in-forward directioh to' conveyvideo components of the IBLUE color:"and assigning phase modulation-of the carrier :in backward direction toconvey video components or the RED color. Then, by employing a colorsequencereversing switch (instantaneous in action), the sequence ofvideo componentsof the BLUE and RED colors may he changed at any randomelemental scansion period, to transmit the sigmail of whichever-color"is present at that time, thereby utilizing greater portion'oi the timethat is available for transmitting video signals a given channel band.When an element consists of three primary colors, the third color isproduced during the succeeding traine period, by simply reversing thetransmission time-sequence of the (RED and BLUE primary colors.

Fig; -1 shows how the color-sequence is reversed elementally. As anexample, ass'um g that in the first original-image-elem'ent oi the framethe BLiUEiprimary color is normally assigned to be conveyed, thereproduced image will contain GREEN and BBUE primary colors. Then, by

the two primary colors are produced simultaneous'l'y in each succeedingframe period. It will reversing the sequence of this ass'igmnent in thebe noted however that when the RED and BLUE primary colors are presentsimultaneously in an image element, some saturation control must beincluded in the system, as the time or phosphor excitation allowed atthe receiving end tor these colors will be less than the time allowed inother color combinations. Since thestoragechar ct istics of colorphosphors may he hired by stane ardization, the magnitude of saturationcontrol may be fixed, depending on whether the RED and BLUE primarycolors are present simultaneously or not.

In accordance with the presently proposed dot-sequential image.scansi'on, Fig. 1d shows one exemplary arrangement of elementalcolor-se quence as produced on the viewing 'screem The first frame showselemental images reproduced individually in different primary-color comaponents; in the second frame the same image elements are reproducedindividually in different primary colors; and in the third frai'neelemental images are finally constructed their three-color hues. Itwillbe noted however that,

at the end of the first three frames every second succeeding imageelement will still contain two primary colors; this sequence beingaltered curing the second three frames, such "as shown the last tworectangles of the drawing. Since according to the color-sequence showhthescansion of GREEN (or other prearranged color primary color isrepeated in every other elemental area, a saturation control is alsorovided for this color; which can he of a fixed value. With theinclusion of the cdlor=scduence reversing switch, as mentioned above,the color sequence as shown Fig. in will vary, since in the absence ofone elemental color (second or third) the other color be scanned:mstead.

I phase is It. wili also he noted from the arrangementor elemehtfiloolordots-shown in the drawing, that none of the primary colors draws a linein any direction the .pictilic frame, for possible line crawl.

The elemental mense ueme shown in Fig. 1c is given only as an exemplaryarrangement for visually effecting high-definition colored pic'- tures'.the viewing screen, when considered in iconiunctioi i with thesimultaneous operation of the colior sequence reversing switch. .Asshown in the drawing, the number of elemental images either lionizontalor vertical direction is adjusted to eN l-l. the event however, when theconventional amplitude modulated transmission is utilized to convey thepresently proposed 'dotasequential-image signals, then the color eemenceof the elemental images may be distributedin fregularsequence (alteringin every succeeding frame), so that all the image elements o the picturemay be constructed in three primary colors at every third frame period;instead of at every alternate third frame, since the.elem'ental'distribution is over only amplitude modulation.

Time-division and simultaneous AM and PH modulation In the general modeof time-division transmission, where theycarrier wave is interruptedabruptly at a high frequency rate, the sidebands usually expand 'beyondundesired frequency regions. However, the output products of themodulated carrier can be restricted to particular frequency regions bycontrolling the waveshape of the time divided carrier envelopes. Wherethese spectral limitations are observed, it is basicthat the waveshapeof the interruption be that of the curve of the sine squared function,which rises and falls from substantially zero caror level hot- :lessthan a definite time period Such wave controlled time division or thecarrier shown at A in Fig. 2, wherein, the "peel: amplitude of eachenvelope represents a mat video sign 1, and the carrier phase in eachenvelope represents a second video signal. In dealing with puremodulation, the carrier "any shifted trepre'sehtative of intelligericc,ag st a reference carrier of constant phase. To -traiislat'e thismodulated carrier into the origin-a1 intelligence, a local referencecarrier is produce at the receiver, and the ph a es of the two caiiiersare compared for dete local generation of the refei''nc'e is impractical,in that, it is diffi cult to retain the frequency and phase of theloc'afl oscillation constant. For this reason, it is cchtem-platedherein to provide means to time div-ide the carrier-waveand shift-thephase angle modulation, and "in new of sideband restrictions;

the earner phase angle "in each envelope is held synthetically :insteady state condition vfrom boundary to bfllwdaiy, shifted abruptly,rep-e,

riesentative of intelligence; at .the' minimum car-' rier level sov asto avoid transient effects between the succeeding phase shifts. 'For athorough understanding of the conditions in which these sidebandrestrictions are obtained, reference may be made to the sideband theorygiven in my secondand fourth patent issues mentioned in the foregoing.

Referring tothe time-divided waveform ofthe carrier at A in Fig.2, it isseen that the video signals are carried over the peaks of the envelopes.Whereas in the conventional mode, the video signals are carried overboth the rise and fall (positive and negative alternations) of theenvelopes. That is, the time of signal resolution allowed in the presenttype of modulation is twice the time that is normally required in theconventional double-sideband"transmission type: with the result thatonly halfof the total number of video components are conveyed overamplitude .modulation, and the other half of the video components areconveyed over phase modulation. Thus in accordance with the U. S.standard of 6 megacycle channel-band, thetotal, number of videocomponents transmitted is 6 million per second (time division of thecarrier. being 3 million envelopes per second), in con trast to the 8million video components that are transmitted over vestigial-sidebandtransmission. This reduction of video components however, is-compensatedby the above mentioned color-sequence-reversing switch of the second andthird primary-color components. Refer ence to the type of simultaneousamplitude and phase modulation employed herein may be made to my UrS.Patent No. 2,558,489 issued June 26,

1951. Video-audio channel interposition video carrier; arising fromaudio modulation.

When these two carriers are combined at differing angles, there willappear other side com ponents arising from both- AM and PH modu1a tions.To either one of these two combinations, when the originalaudio-modulated carrier is readded out-of-phase, then both the audiochannel and all secondary side components arising from cross-modulationwill dissa1,' pear;-remaining only the original video-modulated carrier.

By this example, it is shown that if the audio carrier can be kept freeof videointerference, the video carrier may be receivedby a wide-passcircuit, and the audio carrier filtered out therefrom. Since asexplained, the secondary side components are only resultant at the pointwhere the interposed carrierscombine, such as at the receiving antenna,these, side components will also dissappear by theactofaudio-carrierfilter-- ing. In actual practice however, the video carrier will containa :wide range of -modulation frequencies, which will contribute'to theaudiooarrier, and cannot beeliminated by any filter means.

To obviate this condition, video-to-- audio interference may beeliminated-by way. of.

pre-controllingzthe video carrier phase at the transmitting end. Owingto the fact that many video envelopes of various heights are produced(several hundred) during one cycle period of the highest audiomodulation frequency, it is possible to measure by an interference meter(at the transmitting end) the amount of video contribution imposed uponthe audio carrier, and according to such measurement, reverse 'the videocarrier phase at such random envelope steps, as to balance out the videocontribution falling in the range of audio spectrum. In this step, it isassumed that both video and audio carriers arrive in phase at thereceiving antenna. Also, interference meter is referred to a simulatedaudio receiver at the transmitting end, which according to the amount ofexcitation it receives from the video carrier, operates a carrier-phasereversing device at random short-pulse intervals.

With reference to color television, utilizing simultaneous AM and PHmodulations of the type shown at A in Fig. 2, it had been described thatthe carrier phase in each succeeding envelope shifts forward or backwardrepresentative of an elemental image component'of the second and thirdprimary color in steady state step by an angle that is measurable from apreceding step of the carrier phase. In other words, the referencecarrier phase shifts continually in time division steps. This type ofphase modulation differs from the ordinary type, in that, phase angle ofthe carrier in the ordinary type remains constant whenever themodulating voltage remains constant. Whereas in the present type, thecarrier phase shifts continually in steady state steps; even though themodulating voltage is in a steady'state. In other words, as far as theaudio-carrier is concerned, the video carrier is looked upon as beingfrequency modulated. And because these phase shifts occur at a highfrequency time-division rate, most of the video contribution imposedupon the interposed audio channels will be cancelled out depending uponwhether one or both of the second and third primary colors are present,and the angle at which the carrier phase shifts from envelope toenvelope. However, for complete elimination of video-to-audio carrierinterference, an interference meter is included at the videotransmitting end, to shift the carrier phase randomly in veryshort-pulse intervals, so that color spots on the viewing screen at thereceiving end'wil1 be too small and of short duration to be apparent orobjectionable to the viewing eye.

A number of interposed audio channels may occupy the video spectrum. Butbecause sidecomponents resulting from cross-modulation of v deo-audiochannels will spread over adjacent video channels, the desired videochannel cannot be selected by a circuit having band-pass of onlya'single video channel-width, as the interfering side components cannotbe filtered out without the cancelling-action by the original audiocarriers. Another way of looking at it is that, the secondary sidecomponents are modulated-by video frequencies, and cannot be separatedfromthe selected video frequency modulation. For this reason, theinterposed audiochannels in the selected video-channel and those in theimmediate adjacent video-channels that cause secondary sidebandsspreading over the selected video-channel (arising from phase modulationdue to cross-modulation of the audio and videocarriers) are firstfiltered out by a series "merc nt o sets t 9.5 of: narrow-band; filters.and secondly,. the. video. channel is selected. intheusual manner...When the rate of phase. control of: the carrier: is: such that itscontributionuto. the audio: carriers is barely audible, then there. areused. as. many narrow-band filters as there. are interposed audio-..

channels the. selected videoechannel. How-- ever, the frequency rate. ofvideo-.carrier-phase change may be substantially increased withoutimpairment to the image, and allow the. use of wider-band audio-channelfilters for: reducing their numerical size.

While the description involves a plurality of audio-channelinter-position with that: of the videoechannel, the main purpose'here isto transmit the audio-oarrierfiat the video-carrier frequency forspectrum; conservation and simplicity of the receiving set. Accordinglygand in view-of the foregoing information, the invention in its broadaspects provides the following steps: scanning color-pictures v theusualsense of horizontal and vertical directions in a frame period;including' horizontal and vertical retracings, and deriving therefromfsimultaneous video sig na'ls representing first; seoor'id;"and thirdpri-.

- I arycolo-r components of the image elements,

' time dividingthei eo signals at a frequency rate equal to the hihestnumber of image ele- "ments to be conveyed p'e'rf'sec'ond,producinga has. whe eby ir t to io o the'fi im r e al succeeding imageelesimultaneously convey mea s in ea h sures? me s c d. i fi c sca QnQfth elemenial im es .l ins lar rim rssuh ta ltia lr lementa'lly-difierent:fro I a p ur f am t e? brt fifis tl uti a colora n is all to s 'qhfemai rp jwr a le sc nn r, tbyisu s antially all? th image elements thatwould normallyJoe av lable for monochrome picture, alteringthe sequenceof primaryecolor icomponents of said elemental images d r n r a ively slw f q c r te of Su es v am ,l ii fi, primary-color [com n ts of mdivdual image elements are scan ubstantially coincident during 'succe colorfscansiojn,

sai nhasemed l col com s. lli leq fi gfi s ionsbehind of last said 7carrier envelope, and

a acent 'image' elements onst tuent between, various primary colorcomponents, and

amplitude waveshaping' said modulated ca '.rrief envelopes, in a sensethat, at the boundaries the carrier level is lowered gradually tonegligibly minimum level, thereby to allow wideangle phase shifts of thecarrier at said minimum levels without causing appreciable transienteffects.

There is also provided the steps of producing a soun decarrier-wavehaving the same frequency as said video-carrying wave; or in thevicinity thereof, modulating the amplitude of aforesaid'carrier by soundwaves, measuring the amount of videosignal' contribution. that isimposed upon the sound waves, and according to such measurement, shiftthe phase angle of the carrier in said envelopes periodically, wherebyto cancel out the video-signal contribution periodically during any oneof the sound-wave cycles. Further steps are provided to conveypicture-synchronizing signals over phase modulation of the carrier,whereby to effect greater accuracy in picture-synchronization than maybe achieved by the conventional ampli-' tude modulated serrated form.Still further steps are provided to receive the transmitted signals.These and other features thereof will be better understood from thefollowing detailed specification, with reference to the accompanyingdrawings in which:

Figs. 1 and 1a illustrate scansion sequence of elemental images indifferent primary colors.

In Fig. 2 at A there is shown the waveform of the modulated carrier inaccordance with the invention, and the drawings at B- to E illustratethe steps in which the carrier is modulated in its .final form.

Fig. 3 is a block diagram of the transmitter in accordance with theinvention; Fig. lis a modified arrangement of the transmitter; and Fig.5 illustrates various waveforms describing the operation ofFig.4.

Fig. 6 illustrates waveforms of the modulated carrier wave, in whichphase modulation is utilized to convey picture-synchronizing signals;and Fig. 7 is an arrangement for detecting phasemodulated signals. v

Fig. 8 is a block diagram of the phase modulator for synchronizingsignals; and Fig. 9'illustrates the sequence of pulses representing thevertical and horizontal synchronizing signals for operating thearrangement of Fig. 8.

Fig. 10 is an interference meter in accordance with the invention.

Fig. 11 is a block diagram of color signals in accordance with theinvention: and Fig. 12 is a modified arrangement of same.

Steps in which the carrier envelopes are prodaced In order to modulatethe carrier in the illus'- ,rier envelope may be waveshaped and simul-'taneously amplitude and phase 'modulated, by sampling method, andfinally the periodic out,- puts of the two channels are combined forfinal transmission. For example, at thev output of the first channel,periodic carrier envelopes at B are produced, and at theoutputofthesecond channel, the periodic carrier envelopes at C are produced. I Thenbycombining the periodic carrier envelopes at B and .C, the desiredwaveform as shown atA is obtained. The peak amplitudes of th aerpdicenvsl res fth carrier wave at the receiver of Phase and amplitudemodulated transmitter In the case where two primary-color components ofa single image element are to be conveyed over each time-division of thecarrier wave, the transmitter in Fig. 3 is given. In this arrangement,the carrier wave is produced by two independent low Q oscillators I andII, both of which oscillate at the carrier frequency. The phase angle ofoscillation I is shifted periodically in phase modulator I, by signalsarriving from the RED video source, through normally idle gate 2,-whilethe phase angle of oscillation IIis shifted periodically in alternate,sequence with the former, inphase modulator 3, by signals arriving fromthe-BLUE video source, through normally idle gate 4. The phase modulatedoscillations I and II are applied upon; each other periodically inalternate sequence, to; forcefully shift each others phase angles, byangles representative of RED and BLUE video signals, measurable fromphase angles that the oscillations I and II had resolved in immedatepreceding intervals. This operation is. performed bycross-applying thephase modulated oscillations I and II through normally idle gates 5 and6, which are operated in periodic sequence by the alternate half-cyclewavesof the switching wave at frequency fm/Z, generated inl-blcck. 1.3.This switching wave also operates the .gatesz. and 4 inalternatesequence, .so: that the RED and BLUEvideo signals are admittedtherethrough and modulate the .phase .angles: of oscillations I and IIinphase modulators i and 3. Ordinarily the gates 2 and 4 would not bevnecessary,.but they-are includedfor the purpose of reversing thetime-sequence of RED and BLUE video-signal modulations when, thecolorsignal assigned to an elemental scansion time is -absent,. so that'the' other color-signal can be transmitted instead. achieved asfollows:

voltages of which determine whether the input signals arepresentor notat any given instant.

Due to limiting action, they output voltages of limiters 8 and 9 are ofconstant amplitudes, which are applied additively upon the gates 2 and4. The input cut-offbias voltages of gates 2 and 4 are so adjusted that,they operate only when positivevoltages from limiters 8, 9 andswitchingvlave fni/Z arrive at their inputs simultaneously. Thus, whenboth RED andBLUEvideo signals 'are'presentsimultaneously during anelemental scansion period, the modulation sequence proceeds as nor mallyassigned. Reversal of this sequence is achieved by cross-application ofthe "RED and BLUE video signals upon phase'modulators and 3, throughgates to and I I. These gates are operated by'the alternate positivevoltages from block I, but are normally prevented from operation bynegative voltages arriving from the outputs of limiters 3 and 9, throughphase-inverters l2 and '13. Accordingly; when both RED and BLUE operatesto transmit the normally assigned colorsignal. But when this assignedcolor-signal'is I2 absent, either gate I0 or H is caused to operate,which in turn efiectsIcarrier-phase modulation by the othercolor-signal. Thus, most all of the elemental scansion' periods areutilized for transm1ssion, which otherwise would be lost in regularsequential transmission.

.For color. switching, the signals of video RED color advance thecarrier phase, and the signals of video BLUE, color retard the carrierphase, wherebycolor signals may be automatically selected'at thereceiving end.

As explained previously, when during an elemental scansion period boththe RED and BLUE video signals are present simultaneously, a saturationcontrol must be included in the system. Since this control isfixed, andneed only be on or off during an elemental scansion time, the outputvoltages of gates 8 and 9 are passed through gate 14 to control the gainof RED and BLUE;video sourcesythe bias of gate l4 being so adjusted thatit operates only when the limiters 8 and 9 are active simultaneously.

For combined phase and amplitude modulation,;the periodic steady statephase modulated portions of oscillations I and II are further amplitudemodulatedin steady state steps by video signalsof the GREEN primarycolor. The original Video signalsbf GREEN primary color are sampled inAM -samplers l5 and I6 periodically (as shown-at D and E in Fig. 2) inphase with thesteady statephase; modulated portions of the oscillationsIand II, so that these periodic portions are simultaneously amplitudemodulated ,inthe AM modulators l1 and i8, by the video C REEN-signals.Thus, the outputs of modulators-l] .and I8 contain simultaneousamplitude and phase modulated carrier, in alternate steady state stepsat the time-dividing frequency rate; ,The outputsof these modulators areindependently applied upon the grids of gate-andamplitude -modulatortubes V and V", which are normally rendered inoperative. The plate'voltagesof these tubes are alternately supplied by, the .wave fin/2,which is amplified and waveshapedfsuch as indicated by the waves next toithewa'veshaper blocks 19 and 20. These alter- "Modified arrangement ofthe transmitter It -was' explained in the foregoing that theblockarrangement of Fig. 3 will provide for conveying twocolor-components of an image element simultaneously during eachcarrier-envelope period. Instead, as proposed in the invention, wheneachcarrier envelope is to convey color components of two image elementssimultaneously, then the modified arrangement of the transmitterin Fig.4'is employed, the operation of which is described by way of theillustrated graph diagram in Fig. 5. Statistic magnitudes of'the camerapick-up color-components of imageelements are shown at B, wherein, eachoddsection represents either RED or BLUE primary color of the imageelement, while each even-section represents only GREEN primary color-ofthe "image element;- this color-sequence being retersed' rom netoline.asdeseribedin tlrefore+ oin Brier topr notion. o the. first ca ier lYelope at A,.t e. eel n eem nents El and E at5B are. amp ndstored. so atbot carrie phaseand. P al amplitude o th fi s envelope are modulated bythese signals. More speeifieailv, duri h xtime peri doi. E atthenhaseetea ier sc atio n -t is. shi ted y; a r esentat ve; an le 61.;on O eil a inea that phase. hereaitep. Dur n he time periodoi E2,- at'B, the sampler at i D. (such asthe. Sam lern eer va ie snum rale. be ge.rep at d; in. F 4, iereem ar son of ik ar th h to F aores. a o a e e u oE?- Then, d r ng. he. rs t rrie envel pe; at A ea r r. es i lat en at hei atms t st v a l it. s m lit de modulated by the steady state voltageE2 at D,

and.fine lren ese-shaee i web s sh w by May of the arrangement of Fig. 3or.- 4,' for. radia-r iea- Dutiesh ime, er d i thepha e carrieroscillation II at E} is shifted by a represen at v an l a and hat phasehereaf e Dur ne he tim r o at'B, the sampler at F (such as the samplerIt in Fig." 3 or 4)' storesa voltage equal to E4. Then, during thesecond carrier envelope at A,

the carrier oscillation'lI at E, oscillating concontinues oscillating atmodulating's'ignals'are admitted rer' shifting the phase. angle.ofoscillation I. 'The p'ulses at H opcrate. a discharging elementv for.discharging a storage. condenser in sampler at D. An'd the pjulses'at Ioperate a charging element to store aproportional signalquantityinalstorag'e conedenser, in sampler at The pulsesatlJito fL areproducedi'n alternate sequencewith regard 'tothe pulsesQatfGtoI, inorder to' efiect alternate operation of .f'the'" samplers in first and.sec.- ond branches, of the. transmitter in Fig. 4, for continuousProduction. offthe carrier, envelopes. In Eig, 4,the pulse producers.are shown by theblocks. 22' andv 2'3. These, pulse producers maybearrangedinivarious formsQbut the arrangement shown in my. 'U; S.Patent No 2,5583% issuediJune 2 6; .1951, Fig.. Band by theillustratedpulses atjlqein' Fig ll will be found suitable for the purpose Withreference tq thecolor sequenceshown in r Fig, la, it was describedinthejforegoing that,

a saturation control must be included for the GREEN primary color, inalternate time-divi'sionperiods. Thisis achieved by doubling thefrequency ,fm/2:to in; in block 2 4;-half-waverec tityingi in block 25';and applyingthe periodic output voltages upon the. GREEN'video sourcetogcontrol the gain of thesesignals'.

With reference to color-sequence reversal, it vgilibe noted in the.arrangement of either Fig. 31;: prjfig, 4 that, during. phase-shiftingperiods oiaoscillations, I andlI, the. combined output voltage ofamplitude-limiters 8 ands-must rehorizontal synchronizing pulse,

main; constanti'; either on: on off... em as; mamas crosseswitching.between the. RED: and BLUE videosignals. The. steady: condition; of.limiter 8 and. 9,. is, easily: achieved: by: time. divid g: the originalvideo signals; in phase. withthe; samplin periods, andwaveeshapemthesetimerdividedl Sig:- nals inathe video amplifiers;..s.u.ch: as. by:thelarrangements in; ordinary video. amplifiers, to en.- sure thatduring. .carrier-phaseeshitting; and/ 01 sampling. periodsthe;statisticwidemsignals. do. not change from one: light. level: toanother. isshown in Fig; 4.=, .w herein, the. output. of block 21 5 isfullr-wave r'ectifiedintdunidirectional pulses, and. applied upon. thethree. video signa1 sources for time divisioniotthe signals 5' as mqdtwte a e u se In the drawing of Fig. 6, there. is. shown a waveform ofthe time-divided carrier envelopes, wherein, the time, areas a. are.devoted to the conveyanceof video signals, and the time areas b a evotedo. he onvey nce. of syn en ing pulses. In thefirst section of areas b,the carrier phasev is shiftedQQ degrees backward in every succeedin i.elciiqe;w rep en n t e n t eeqnd section of areasb, the .carrierphase;isshiftedso degree forward. in very.- ue ee ins. e elo e: r pr sen inthevertiea nchron zing-pulse; foieven-line. And the. thirclis etien 9i25. 12 ca ier. p ase. is shi ted. backward; and. wa sequentia lyv from.env lope t9... enve o e; e esenting simultaneous hpri zontat andvertical pulses; for odd-line... Thenum er carriern;- v opedurinaeaehsvnchmnizi anulse;i 0.1? no importance, but it'iszdependent.upontheduration of the phase:modulating pulse atthe transmit ting, end,Phasc discriminator jo'rvideo-signals and for horie-vertsynepulses Inthe firststep otdetectingthe phase modulated carrier wave the amplitudevariations'of the carrier envelopes are limited as -indicated by the dotand dashed lines c-, in Fig. 6. When the carrier envelopes are thuslimited inamplitude,

the output-will be (disregarding thenarrow dips between the envelopes);as i-f thecarrier-were of c o'ns'tant amplitude and'that the phase anglethat, the anodec-i-rcuit of amplifier-tube'v comprises a resistance R,in seriesfwith the resonant circuit LI having a resolution timeconstantequal to one time-division period. Thus, at the beginningof-feach time-division, the-carrier phase inlt and LI will differuby'ananglethat is a function of theincomingvideosignal; this phasedifference graduallyresolving into in-phase relation at the endotaeach-time division. Dueto the nermal quadrature phaseirel'ationbetween Ll and- L2, and therefore; normal; quadrature phase relationbetweenthevol-tagesacross R4 and- L2,

and also due to the-symmetric connections of diodes Vi and f V2,-the-voltage from cathode terminal tov groundwilLnormalIy be zero. Whenthe incoming carrier, shifts its; phase in forward direction, thecathode-terminal of di'ode Vl=- will be more negative than at thecathode terminal ofiV Z Whereas, when the-phase shifts-in back wardidirection, the cathode sideo f V I; will be morepositive'a- -'Ehesepositiveand negative out This put'voltages are furtherrectifiedbyfldiodes V3 and'V i, so as to obtain independentoutput'signals representing video signals of different primarycolors,which are amplified by the video amplifiers in blocks 2M3 and 21.The amplitude modulated video signals (GREEN primaiy color in this case)are amplitude detected (not shown in the diagram), and amplified bythe'video amplifier in block '28; the outputs of the three videoamplifiers are then applied upon the control grids of a color-imagereproducing device:

For the separation of picture synchronizing pulses, the outputs of videoamplifiers 26 andl'l are separately applied upon one1of the .:controlgrids of multicontrol electron'tubes V5 and VB,

which are normallybiased to anode current cutoff. The output of videoamplifier 28 is applied upon the other control grids of these tubes in Iparallel. Due to the "extreme negative bias applied upon the controlgrids of these gate tubes,

anode current fiows'only when positive voltages are applied to bothcontrolgrids simultaneously. Thus, when the amplitude of "the videocarrier is raised above a predeterminedlevel at the transmitting end,assignedas synchronizing-level, the output voltage of'video amplifier 28raises the potentials upon the second control grids ofgate tubes V5 andV6 to'theoperating point, so that 'the phase-modulatedsynchronizingpulses from the outputs of video'amplifiers 2B and 21 operate one orboth of the gate tubes for picture synchro- 'nization. The amplituderise of the carrier wave to synchronizing level is achieved by thearrangement shown in Fig. 3, wherein, the block designated as, syncpulse,- applies negative pulse to the i Phase modulator-0f sync'pulsesFig. sis a modification ofthe block diagrams in Fig. 3 or 4, but in thiscase, only phase modulation is shown. The outputs of oscillators I andII are split in-phase 90 degrees by the transformers n T2 apd'a i d. ndeendent .upon the control grids of phase modulator tubes V's, V8 and V9,V10. 'The cathode bias of modulator tube V8 is'so adjusted that the tubenormally operates at its maximum transconductance. Whereas, the cathodebias of tube V1 is so adjusted that the tube normally operates at itsminimum transconductance; these adjustments beingsuch that, the Gm curvebetween maximum and minimum is substantially linear. Thus, the anodecircuit of tube .V8. normally cone tains maximum oscillatory current,and theanode of tube V? normally contains minimum oscillatory current.The-anode circuit, comprising transformer T3, further shifts the phaseangle of the output wave by 90 degrees, and applies upon the oscillatorII,-in the same phase angle as it originatedin the oscillator I; Whenthe positive video RED signalarrives at the control grid ofcathodefollower and phase inverter tube Vi I, the video signal isapplied upon the second control grid of V1 inpositive polarity, and uponthe second controlgrid of V8 in negative polarity. In this manner,the-transconductance of tube V! is increased, and the;transconductanceof tube V8 is decreased with the result that the phase angle ofoscillation I in transformer T3 is shifted iorwardin its applicationupon the oscillator II.

The-operation of phase modulator tubes V9 and Wills similar totheoperation of V1 and V8, but in this case, the BLUE phase-modulatedoscillatio'ri'II retards the phase angle of oscillation I, by "reason ofthe inverted connection of transfQrmerTZ;

The output oscillation of I after being phase modulated by the RED videosignal, it is applied upon'the oscillator II, through gate 29, while theoutput oscillation II- after being phase modulated by the BLUE videosignal, it is applied upon the oscillator I, through gate 30. The gates29 and 30 are operated in alternate time periods by the alternatepositive half-cycle voltages of the timedividi'ngwave produced in block3!. For the video-signalmodulation, the output of oscillator I" (at-op)contains periodic steady state phase modulations representative of i thevideo BLUE signals, and the output of oscillator II (at op) containsperiodic steady state phase modulations representative of the video REDsignals; in sequence with respect'to each other. In the casewhenimage-multiplexing is employed, such as described byway of theillustration in Fig. 5, and 'theblock arrangement of Fig. 4, then theoscillations I and II are time divided by the blocks 22 Thesynchronizing pulses are generated in positive polarity-at the outputterminals X, X and Xf of block 32 in theform as shown in Fig. 9.Simultaneously with'these pulses, there are produced pulses in negativepolarity, as indicated at the, extreme end terminals of block 32, whichare applied upon the gates 29 and 30 to render them inoperative, andprevent the signal modulation from interfering With'the'pulsemodulation. The gates 33, 34 and 35, 36 are normally renderedinoperative, and are so arranged that, they operate-only whensimultaneous positive voltages-are applied upon, by the alternatepositive half-cyclevoltage of the time-dividing wave inblock 3i and thepositive pulse from the pulse generator}; j The output oscillation Iafter being phase-retarded by the transformer Tl isiapplied'upon' theinputs of gates 34 and 36 simultaneously, while the output oscillationII afterbeing 93 phase-retarded by the transformerfIZ is applied uponthe inputs of gates 33 and ,35 simultaneously. The output voltages ofgates 33*and 34:31? phase inverted by the blocks 3'! 'and'i38, so thatwhen the gates 33 and 34 are foperated alternately by'the simultaneoussynchronizing positive-pulse from block 32 and al- 't'ernate.halfcyelepositive-voltages from block 3l, the oscillations I and II will beadvanced in phaseI'byQO degrees in 'every succeeding halfcycle periodsof fm/Z. The outputs of gates 35 and 36' are applied in phase upon theoscillators I and II, soth'at'when the latter gates are operated; thistime the oscillations I and II will be retarded in phase by 90 degreesin every succeedin alternate intervals of the wave fm/Z. Whenhoweventhepulse generator applies a positive pulse upon gates 34 and 35simultaneously, the oscillation II passing through gate 35 retards thephase 3 angle of oscillation I, and the oscillation I passing throughgate 34 advances the phase angle of oscillation II, causing sequentialphaseretarding and phase-advancing of the carrier wave from envelope toenvelope. In this case, and with reference to the phase discriminator inFig. 7, both the vertical and horizontal scannings are acted uponsimultaneously, for odd-line field scanning s j and phase-video.-detectors. v

- detector isappliedauponthe input of video BLUE ise'qwence of syncpulses ,-.The distribution sequence. of horizontalv and vertical. pulsesis shown in Fig. 9. At PI, both the vertical andhorizontal pulses at Xare pres-.

the horizontal and vertical pulses appear at X;

fora new start ofitheioddlines.

Interference 'meter "fOne. type. oi'interference meter is shown inFig.110. The output of video transmitter is applied upon the narrow-bandreceiver simultaneously with'the outputoi, oscillator fca, whichsimulates as'an interposed audio-channel. In the absenee'of thevideo-transmitter output, the oscillator output represents zero signal.Whereas in'fthe presence of video-transmitter output, the oscillation atfrequency fca will bemodulated'.

Whenthismodulation is in the audio-frequency rangeyitrwill be detectedand amplified by the AFamplifi'er. 'In the drawing, there is shown apulse generator, which produces short pulses 8177501116" predeterminedintervals. ihese pulses p the envelopes.

=a're"applied upon the first control. grid of V the gate tub'e,.'inpositive polarity. Simultaneously; the output of. AF amplifier isappliedgupon'the'second J'con'trol grid of the gate tubefal'sofinpositivepolarity. The control grids offthis-gate tube are so biasedthat, it operates byth'e' pulsesonly'when a simultaneous output voltagearrives from the .AF amplifier.

with'the' presence of AF signals, the pulses will Thus,

appear at "the output impedance 2, which are applied upon one 'oftheiphasemodulators of the transmitter in Fig. 3on4, as designated bythe lottery; Such phaseshift of the video carrier w tendt'o' opposethe'oscill'ation fee, and reduce t e outputof the 'AF. amplifier,indicating ,that the mterposed"audio channel is free offvideo 'in--ter'ference. The oscillator fee. is shown in. the

drawing'for illustration, but it is 'notnecessary.

actual practice; .althoughit may also be obtainedand used'from theactual audio-carrier.

Receiver eig..;11. is-a-block'diagrampfone form ofthe receiver, which.-may .be employed-in accordance vikiththeinventiom The incoming-wave ispassed through. anBE stage; IFstages; a Hike-wide 'rejectiohfiltertocancel. out theaudio modulation; .andfinally demodulated by theamplitude The 1 output of AM ampl'ifier-,..and the output of PH detectoris sup- *pli'edup'on .the video GREEN and RED; ampli- 'the control gridsof a tri-color image tube for final'color-picture reproduction. Forsound reproduction, output of the I. F. stages is passed throug'h-a-band-passl circuit of l0kc. width, the

outputofwhich is amplitude detected, as shown in theidrawing. I"Ii-howeven'the soundwaves are transmitted 'ovena carrier wave, havinga,frev the rejection filter is eliminated, and the sound wave is detectedin the conventional manner;-in either case of amplitude orfrequencymodulation.

Modified arrangement of-receiver Referring back to the type, ofvidezomodulation, as shown in Fig. 2, and disregarding the phasemodulation for the moment, it is seen that the video signals are carriedover the peaksof Whereas in the" conventional modethe signals arecarried over both the rise and fall (positive and negative alternations)of the envelopes. That is, the time of signal resolution allowed in'thepresent type of modulation is twice the time that is normally requiredin the conventional type; causing a waste of useful latory signals inwhich are periodically built-up and dissipated; the-method of whichis'sometimes used in diversity receivers. I

Fig. 12 is a modified arrangement of the receiver, wherein, the incomingwave is passed through wide-band R.- F. and I. F. stages, the output ofwhich is applied upon two separate high circuits, LI and L2. The highfrequency voltages across coils LI and L2 are passed through the gatetubes a and b,during alternate half-cycle voltages across L, at afrequency of 1.5"megacycles. The poles across coils L, as well as thediodes Di and D2 are so arranged-that, when gate a is switched on, thediodeDl is idle, and coil Li starts building proportional" amplitudeotoscill'atory voltage; while gate' bis switched on, and diodDZ clampsoutthe oscillatory voltage across coil L2, and vice versa. "The periodicoutputs of coils L! and L2 are then combined atth'e outputs ofgates'a'an'd b, for amplitude and phase detection;

fThe modified arrangement "in Fig.;12 is particularly suitable whenmultiplexing of image ele-- ments is employed at'the transmitting end,such as described by way of the graphical illustration in" Fig. '5. DueLto the slow rising oscillatory current in'coils Li and L2, the peakofthe'output envelope will shifttothe right, as shown by *the dottedcurve immediately above block diagrams of the AlVl-detector. Then, bythe gated action, the curve is changed to the form as shown by the solidline. When the combined outputs of coils LI and L2 are phase detected,after passing through thel amplitude limiter, as shown, the peak of: theenvelope will shift to. th'e left, as shown by the curve immediatelybelow block diagram of the PEI-detector. This condition was explained'byiway of the phase detector. of Fig.7. The oppositely peak displacedoutput voltages of the amplitude; and phase detectors are then switchedon and off, either at the video-amplifiers'lor the three individualcontrol grids of a tri-colorimage reproducing tube, by the alternatingwave at3 megacycles, which is obtained from theblock'of'high Q tunedcircuitat 3 megacycles; .In the drawing, outputs otthephase.

fier. *Outputs of these video amplifiers are inthe first two cathodes inparallel, and applied i upon the third cathode through the phaseinverter for alternate switching. Since the switching wave a 3 me. isderived from the incoming time-divided carrierenvelopes, both frequencyand phase of the switching wave is permanently fixed. With reference toshifting of the amplitude and phase modulated video signals in timeposition, it will be noted that such shift in time position may also beachieved by a delay-line.

While I have described what is at present considered the preferredembodiment of the invention, it will be obvious to the skilled in theart that, various substitutions of parts, adaptations and modificationsare possible without departing from the spirit and scope thereof.

What is claimed is:

1. In color television where each scanned image element is conveyed inseparate primary-color components, the system of producing andtransmitting video signals in values representing primary-colorcomponents of the image elements, which comprises: means for scanningcolor-pictures in the usual sense of horizontal and vertical directionsin a frame period; includinghorizontal and vertical retracings, andmeans to derive therefrom simultaneous video signals representing first;second; and third primary-color components of the image elements, meansfor time dividing the video signals at a frequency rate equal to thehighest number of image elements to be conveyed per second, means forproducing a carrier wave and means therefor for time dividing it intoindividual envelopes at a frequency rate equal half that of thetime-divided image elements, means for modulating the carrier amplitudestep by step in every succeed: ing envelope by the first primary-colorcomponents of every second of the time-divided image elements, means foradvancing the phase angle of the carrier wave step by step in everysecond envelope by the second primary-color components of every fourthof the time-divided image elements; lying in time positions ahead oflast said every second image elements, means for retarding the phaseangle of the carrier wave step by step in every other second envelope bythe third primary-color components of every fourth of the time-dividedimage elements; lying in time positions behind of last said every secondimage elements, whereby first, to provide modulation of each carrierenvelope by simultaneous sets of two succeeding image elements indifferent primary colors, and second, to provide scansion of elementalimages in singular primary-colors substantially elementally-differentfrom adjacent image elements in a picture frame so as to effectmutual-aid in visually forming chromatic-picture in a singlescanned-frame by substantially all the image elements that wouldnormally be available for monochrome-picture in a single frame, meansfor altering the scansion sequence of primary-color components of saidelemental images during relatively slow frequency rate of successiveframe periods, whereby said image elements are further resolvedindividuallyinto their full three-color hues during successive frameperiods, and means for transmitting the modulated carrier envelopes.

2. The system as set forth in claim 1, which includes means forcontrolling the amplitude level of said color components duringelemental scansions, whereby to correct distortion in hue that may occurat various elemental areas due to differences in average time-lengths ofscansi on devoted to each primary-color of the image elements.

3. The system as set forth in claim 1, wherein, said phase-advancing andphase-retarding means consist in combination means for shifting thecarrier phase in said succeeding envelopes step by step representativeof said color components by difference-angles measurable from phaseangles of the carrier in immediate preceding envelopes, so that theangle in each step of phase change represents a reference angle to asucceeding step of phase change.

4. The system as set forth in claim 1, which includes means forreceiving said transmitted carrier envelopes, means for derivingseparate video signals from said amplitude; phase-advancing; andphase-retarding modulated carrier envelopes, a color-image reproducingdevice, and means for controlling the operation of said device by saidderived signals for the final reproduction of the originalcolor-picture.

5. The system as set forth in claim 1, which includes means forreceiving said transmitted carrier envelopes, means for derivingseparate video signals from said amplitude; phase-advancing; andphase-retarding modulated carrier envelopes, means for shifting thetime-positions of video signals derived from said amplitude and phasemodulations in harmony with the original time-positions of saidtime-divided image elements, and means for operating appropriatecolor-picture reproducing apparatus by said timeshifted video signalsfor the final reproduction of the original color-picture.

6. The system as set forth in claim 1, which includes means forproducing and transmitting a sound-carrying wave having a fundamentalfrequency lying in the spectrum band of the video signals, means forproducing sound waves, means for modulating the amplitude of saidsoundcarrying wave by said sound waves, means for measuring the amountof video-signal contribution that is imposed upon the sound-wave, andaccording to such measurement,means for shifting the phase angle of thecarrier in said videoenvelopes periodically, whereby to cancel out thevideo-signal contribution periodically during any one of the sound-wavecycles, means for receiving both of said video and sound carrier-waves,means for cancelling out the sound carrier wave and its modulationsthereof from the video car-- rier-wave, means for separating sound-wavesand video-signals from said amplitude; phaseadvancing; andphase-retarding modulations, means for shifting the time-positions ofvideo signals derived from said amplitude and phase modulations inharmony with the original timepositions of said time-divided imageelements,

and means for operating a color-picture reproducing device by last saidtime-shifted video signals.

'7. The system as set forth in claim 1, which includes means forproducing and transmitting sound-carrying wave having a fundamentalfrequency lying in the spectrum band of the video signals, means forproducing sound waves, means for modulating the amplitude of saidsound-cardirection from envelope v shifts in :siequentiai a fryingwavebyisaidr'sound waves,'zmeans' ionmeasairing the amount: .ofwider:i-zs'rg'nalt-icontrihution that is vimposedvupon the :soand waive;v amiial:-

cordingto "such" fimeasur'em'enw mean's :fo shifting: the phase'anglexofrthe'carrier::inz s-ald video- 5 envelopes iperiodicallmiwhereby to fcaneel on-tithevideoes'i'gnalhcontributionsp'eriodica-ll'gfl dliringl ehy ofthe:.'soundwave'zcycle', isai a" measuringi ans comprising zi a ieir'cuit 1 tuned.to" the "fundamental carrierefreqiieney and having. narrow: band -passto admit :soundmzavew modulations only means for shifting .the videomodulated cari ier"Wave upon the input of ilastrsaidi-tuned circuit,means to demodulateithepntputf carriers of any lowfrequency modulationsthatzpassthr'ough the 'cir- I cuit; a pulse generatorproducing:"s'l-iort pulses at predetermined intervalsi la norn'rral l-ynonopera tive-gate, means iforapplying last -said pulse and saiddemodulatedisignalsiuponrsaid gat simultaneously; Jsaidxgatebeing 1 so:adjiist'ed at 29 v itw operates oniy'whenisimui taneous lpulse andidemodulatews'igna'ls are present, whereby sai gate operates during aplied-pulsex'whensaid: elemodulatedssignaiis pr'esennoan 7 f plyingitheoutput signal iofi saidug 2.3 of said .ph'ase modulators "of thevideo-carrier waiveyso as to shi-ft the "carrier phase by way o'fcarrier wavewoppositiom until saia demodulated signal disappears.

The; system :asaset for-1th in c'iaim-.l; which includes: means? fortransmitting: :pictnrees'ym chron'izihg. pulses: Idur-i'ngz saidhorizontal and to envelopeinconti u'ous representing 1 the honi'zontsteps; said phase' shi s representing ta thescornposite 'mcdn a e31selectmg the ampntuee; :p'has'e ae ni phase-retarding carriersignal-moiinlations-from the carrier amputees-level assigned to signalmodulations; to operate appropriate color-pic- V ture -rproducingapparatus, and means 'for'selecting thei'synchronizihg 'piilses from?the carrier amplitude-level assigned to pulse nodu-lations"; lto'operate appropriatepict -ue-synchronisingljapparatns for finalreproduction of the color- (30 a picture.

i 9 ,lIn-color television system -apparatus which comprises incombination the-Qitillowin par-ts: means for scanning color-pictures inthe aerial sense of horizontal" and. vertieaLd-irections: n -a frameperiod, and means'therefor for deriving therefrom simultaneous videosignals rep-resenting first; second; and third primary-color componentsof the image elements, a switching Wave, and means therefor fortime-dividing the 'video To signals at a frequency rate equal to thehighest number of image elements to be conveyed per second, meansforproducing a carrier oscillation in first and second channels,cross-coupled first and second gates relative to the first and 7'5'ti'o'ns-l in first and second channel's 's'h .v image'eIemeiits-lfingin tiniea lastsaid everysecone element g means v for' retar'ding thephase time' iiiyide'd meg e elements lyirig tin-1 'sition tennis orlast-said every second I elements,m'eajns for advariein'g' theeutpuooloe omponents-oi eve y-- divided *rmage momentsing '1 ingthe 22second: channelsr alterfiating switching 'wav'e having-one fourth of thetiine divided frequency, and means i therefor 501 o erating the 1 firstand second gates-alternatel whereby "the ose'il lanodsuunngwhich-theoscillations-are iiI -S te d'y states-means: for -a inlitude' modulating he Steady State' -pbftidh's 0f the-carrier osciil'aitin the fi'i's t and- "Second channels 'in stead'ys te steps by the"firstpr-i'mery-comr components-i0? every Stind 0f "the time-dividedimage -1m fifth and si-Xth 'gates a-nd 'firstphase' ino'dui' oiassociated with 1 the first channel; seventh (i eighth gates ane'se'conel- 'phase modulator s= 'soc'ieltiid" With 'the second channelmeans ror rendring'the fifth and seventh "gates u'st short bfoperationwanwthe 'S iX'th and Gig hjga'tes' operative; alternately by'seiid SLItlfl'fiiliQfiWifihiii'g' means for advancingthe' pha e" 1e ofoutput oscillation ofthe 'first' channel the first "phase mo ematorthrough the *Yfift be by the second primary-color eeni 'one s o ei' y'fo'l'irth "of" the time-minded *imag'e '-elltl'ehts 3''- ingtime-positions eiliead bfsaid eve orrdfiinageelements,-ihearis forretardm he phase angle of output Oscillation of the sec channel in"th-enrst ehase modulator-throu h the sixth gate'bythe third rimary' 'lorcmponents-=ofevery iourth o ti positions hehind of igle o'f outsetes'eillation" or the second jehann l' in the-second moderator threu h'the seventh-gate h'ythe hir'ci primary coloiifcornponentsof everrourt helation ofthe second channel the secon phase modulator -through theeighth gate the sem and primar oolor oemponents of every eon-rm of thetime-divided image elements lyi in time-positions ahead-bi last said'every se ond i'ma'ge" elements ei-seand "e'co'nd amplitudel-ifn meansfor appiyi-n second p ima y aheaw and" -"i5e'nind or said eve-r seeelement's upon-"the fir d'fpriniary-eolo'r o p said everi iourthoftheima eelements upo second iirniter: -wisereby the output for thefirst rsare substantially-either oftnepenaing on whether the p tsrgna eprese t or not, means for zappiyiiigithe-outmrt of thefirst'limiterwupon -the'fi fth gate to render it operative by thesimultaneous application of said alternating switching Wave; means forsimultaneously applying the output of the first limiter upon the sixthgate in opposite polarity so as to render it inoperative,wherebythe outeput oscillation of the first channel is phase modulated by the normallyassigned video signal I when it is present at a given time-divisioninsignal when the former is not present at that time, means for applyingthe output of the sec ond limiter upon the seventh gate to render itoperative by the simultaneous application of said alternating switchingwave; means for simultaneously applying the output of the second limiterupon the eighth gate in opposite polarity so as to render itinoperative, whereby the output oscillation of the second channel isphase modulated by the normally assigned video sig nal when it ispresent at a given time-division interval and phase modulated by theother signal when the former is not present at that time, means forcross-applying the outputs of said first and second phase modulatorsupon the inputs of said first and second channel through the alternatelyoperated first and second gates, whereby to effect at the combinedcommon output of the third and fourth gates carrier oscillation whoseamplitude is shifted in steady-state steps representative of the videosignals at the carrier time-division frequency rate; and whose angle isshifted in steady state steps by representative angles measurable fromphase angles of the carrier in preceding time-division steps, means fortime dividing the combined carrier wave into individual envelopes inphase with the outputs of last mentioned gates, waveshaping the rise andfall of last said envelopes to that of the simple curve of thesine-squared function, thereby to avoid widely expanded multiple pairsof complementary sidebands that are usually associated with steep sidedrise and fall of the carrier envelopes, and means for transmitting same.7

10. Apparatus as set forth in claim 9, which includes means forcontrolling the amplitude level of said color components so as tocorrect distortion in hue that may occur at various elemental areas dueto differences in average time-lengths of .scansion between variousprimary-color components, which comprises means for combining theoutputs of said first and second amplitude limiters, a ninth gateoperative only by the combined additive outputs of said limiters, meansfor mediate wave, first and second relatively low-decrement circuitstuned to last said wave, means for applying last said wave upon thefirst and second tuned circuits, first diode or diodes and firstimpedance or impedances connected in series across said first circuit;second diode or diodes and second impedance or impedances connected inseries across said second circuit, whereby said diodes may damp outoscillatory energy when present in said circuits at a relatively rapidrate, first and second gates, means for applying said derivedalternating switching wave alternately upon said first and second diodesand the first and second gates to operate same, in such timedividedintervals as when the first gate is operative the first diode isinoperative while the second diode is operative, and vice versa, wherebythe intermediate frequency wave is built up in the first and secondcircuits alternately; rising in amplitude slowly during eachtime-divided envelope period, and thereby shifting the peak amplitudecloser to the end of the envelope, means for combining the alternateoutputs of said gates at a common output, means for detecting the videosignals of said first primary-color components from the amplitudevariations of last said output, means for substantially limiting theamplitude variations of last said output, whereby to obtain theintermediate frequency output wave substantially in constant amplitude,a third circuit tuned to last said wave having phase resolutiontimeconstant approximately equal to one time-divided period; and afourth circuit having high resolution time constant, means for applyingsaid amplitude-limited wave upon the third and fourth circuits, therebycausing greater amount of oscillatory phase difference in the third andfourth circuits at the beginning than at the end of each time-dividedcarrier envelope, means for deriving video signals of said second andthird primarycolor components from last said phase differences. wherebythe amplitude peaks of the derived signals are shifted toward thebeginning of each envelope, a tri-color image reproducing device havingfirst; second; and third control elements, and meansfor applyinglastsaid derived first; second; and third video signals upon theirrespective last said control elements for final reproduction of theoriginal color-picture.

12. The system as set forth in claim 1, which includes in combination,means for reversing the normal sequence of said phase-modulating secondand third primary-color components randomly at elementalcarrier-envelope periods depending onv which of the two color componentsis present or predominates the other, whereby greater portion of thetotal efiective time devoted to conveyance of video signals is utilizedto further the color and image resolution.

MEGUER V. KALFAIAN.

References Cited in the file of this patent UNITED STATES PATENTS

